The internal emulated disk on MP3000 does not perform as well as externally attached (via channels) DASD.
Also, on the MP3000, the internal ethernet adapters do not perform as well as externally channel attached controllers or the OSA2 cards on other S/390. One other thing to check is compare the physical connection between your MP3000 ethernet and the switch/hub. Is it running at full duplex? How does this compare to the connection on the NT box. Remember, if you are using internal DASD and the internal MP3000 ethernet, I think they both go over the same bus.
